Field of the Invention
The invention relates to motor-driven chimney draft systems used for assisting or supplementing the thermally induced draft in a chimney.
Description of the Related Art
Motor-driven chimney draft systems are used when the thermally induced chimney draft is insufficient. This is the case when the temperature in the chimney has not yet reached a level where the thermally induced draft is sufficient for a proper combustion and operation of the system. A motor-driven chimney draft system supplements an insufficient thermally induced draft, and the forced draft increases the flow of flue gases which are removed from a furnace, a stove or other fireplace, which in turn draws fresh air into the furnace to support the combustion. After some time the combustion may have reached a stage where the thermally induced draft is sufficient and the motor-driven chimney draft system can be deactivated.
In existing motor-driven chimney draft systems the flue gases are forced to change flow direction which increases the flow resistance, which is undesirable.
Flue gases can be very hot, and although some cooling will take place on their way from the fireplace to the flue gas outlet of the chimney, the flue gases can still be hot when leaving the flue gas outlet of the chimney. Chimney draft system including its motor must therefore be constructed to operate at elevated temperatures caused by the flue gases.
It is desirable that motor-driven chimney draft systems add as little as possible flow resistance to the flow path of flue gases. It is also desirable that the motor is protected from excessive heating by the flue gases so that no arrangements, or only cost-effective arrangements, need be taken for preventing excessive heating of the motor.